Rotating machines, such as electric motors and generators, generally comprise a rotating part that is rotatably supported with respect to a stationary part with the aid of bearings which can be for example ball bearings, roller bearings, or slide bearings. Bearings of the kind mentioned above require lubrication in order to operate properly. In conjunction with ball and roller bearings, the lubrication can be for example grease lubrication, oil spray lubrication, or oil-bath lubrication. In many cases, it can be difficult or inconvenient to arrange oil spray lubrication or oil-bath lubrication and thus there is a need for grease lubrication.
The grease lubrication is typically arranged so that lubrication grease is pressed into a bearing via a grease channel that is connected to a reception interface for receiving the lubrication grease from an external source. The reception interface can be for example a grease nipple and the external source can be for example a grease gun. When new lubrication grease is pressed into the bearing, the new lubrication grease pushes old lubrication grease out from the bearing via an exit conduit. The exit conduit is typically provided with a plug which is removed in order to allow the old lubrication grease to come out when the new lubrication grease is being pressed into the bearing.
A challenge related to the above-described grease lubrication is a need for different mechanical constructions for different operating positions. For example, a grease channel and an exit conduit which are suitable for cases where the axis of rotation of a rotating part is horizontal may be unsuitable for cases where the axis of rotation is vertical. Furthermore, in machines where the axis of rotation is vertical, it may be challenging to arrange the removal of old lubrication grease from an upper bearing so that the old lubrication grease leaking out from the upper bearing is kept away from areas of the machine where it could cause harm, e.g. an airgap of an electric machine. Thus, in many machines where the axis of rotation is vertical, there is a need for a bearing housing that is external to the main body of the machine. As evident, the external bearing housing increases the complexity of the machine.